Subscribe2 stopped sending emails

After you updated “User Role Editor” to version 4.3. you may meet the problem with plugin “Subscribe2”.
If you use Subscribe2 plugin at WordPress multisite with “User Role Editor” together, you may discover that Subscribe2 stopped sending emails after new posts are published.
The reason of this problem is simple: Subscribe2 checks if there was blog switching and interrupts email send operation if answer is positive.
File classes/class-s2-core.php:

/**
Sends an email notification of a new post
*/
function publish($post, $preview = '') {
	if ( !$post ) { return $post; }
		if ( $this->s2_mu && !apply_filters('s2_allow_site_switching', $this->site_switching) ) {
		global $switched;
		if ( $switched ) { return; }
	}

And “User Role Editor” really makes blog switching to main one and back to the current in order to load plugin settings from the main blog options database table.
Thanks to the “Subscribe2” plugin author, he added special filter to allow you ignore this checking. Add it to you active theme functions.php file and you restore Subscribe2 normal work:

add_filter('s2_allow_site_switching', 's2_allow_site_switching');
function s2_allow_site_switching($allow) {

  return true;
  
}